# In Cixin Liu’s “Remembrance of Earth's Past" trilogy, why does it take the Trisolaran fleet 400 years to reach the solar system?

In Cixin Liu’s Remembrance of Earth's Past trilogy, why does it take the Trisolaran fleet 400 years to reach the solar system if it can achieve a speed of 1/10 the speed of light, given that Alpha Centauri is only 4.4 light years away? Even accounting for a 1g acceleration then deceleration, wouldn’t it take only 50 years or so?

• Simple arithmetic would suggest that a vessel traveling at 0.1 the speed of light would take at least 40 years to cover a distance of 4 light years or more, and that's assuming it traveled at its top speed constantly from start to finish. If the journey actually took 400 years rather than 40, it would suggest the vessel was only moving at around 0.01 the speed of light rather than 0.1. Not sure any of this is on-topic for this site though. Apr 6, 2021 at 14:14
• In the novel it is stated that the Trisolaran feet can travel at 1/10 the speed of light, hence my confusion. Apr 6, 2021 at 14:16
• I haven't read those books, but perhaps the 400 years figure is some sort of typo or miscalculation on the author's part then, and the correct journey time was approximately 40 years, rounding down to one significant figure. It does seem noteworthy that the actual figure given (400 years) is precisely 10 times what it should be (if the given speed is correct), and that the numerical inconsistency can be rectified by simply removing a zero from 400. Apr 6, 2021 at 14:34
• @LogicDictates It is not an error; it is a major part of the plot. (The actual figure is something like 450 years, IIRC.) Apr 6, 2021 at 14:38
• @DavidW Since they plan to colonize earth I assumed they can withstand 1g, but you're right, there's no evidence of it. Perhaps they can only achieve a much smaller acceleration, about 0.0001g assuming they reach their stated top speed of 1/10 speed of light at mid course, if my calculations are correct. Apr 6, 2021 at 15:12

This apparent paradox is addressed explicitly by Liu when Ye Wenjie is being interrogated. Just as the OP asks:

INTERROGATOR: Then I have a question. If the Trisolaran Fleet that had been launched is capable of flight at one-tenth the speed of light, it should take only forty years to reach the solar system. So why do you say that it would take more than four hundred years?